4,552 research outputs found
Undercover EUV Solar Jets Observed by the Interface Region Imaging Spectrograph
It is well-known that extreme ultraviolet emission emitted at the solar
surface is absorbed by overlying cool plasma. Especially in active regions dark
lanes in EUV images suggest that much of the surface activity is obscured.
Simultaneous observations from IRIS, consisting of UV spectra and slit-jaw
images give vital information with sub-arcsecond spatial resolution on the
dynamics of jets not seen in EUV images. We studied a series of small jets from
recently formed bipole pairs beside the trailing spot of active region 11991,
which occurred on 2014 March 5 from 15:02:21 UT to 17:04:07 UT. There were
collimated outflows with bright roots in the SJI 1400 {\AA} (transition region)
and 2796 {\AA} (upper chromosphere) that were mostly not seen in AIA 304 {\AA}
(transition region) and AIA 171 \AA\ (lower corona) images. The Si IV spectra
show strong blue-wing but no red-wing enhancements in the line profiles of the
ejecta for all recurrent jets indicating outward flows without twists. We see
two types of Mg II line profiles produced by the jets spires: reversed and
non-reversed. Mg II lines remain optically thick but turn into optically thin
in the highly Doppler shifted wings.The energy flux contained in each recurrent
jet is estimated using a velocity differential emission measure technique which
measures the emitting power of the plasma as a function of line-of-sight
velocity. We found that all the recurrent jets release similar energy (10
erg cm s ) toward the corona and the downward component is less
than 3\%.Comment: Accepted for publication in ApJ, 6 fiugre
Minimum intervention children's dentistry - the starting point for a lifetime of oral health
Child-friendly minimum intervention dentistry (MID) dominates modern thinking and practice around delivery of oral care for children. It is an enormous challenge for our profession to move away from the narrow focus of a mechanistic, cavity-orientated surgical approach for managing dental caries to one which embraces new strategies for caries prevention and management, delivered in the context of a partnership with children, families and other adults involved in the child's life environment. It is also time for a shift in the orientation of dentistry towards 'patient self-care' becoming a core goal of dental care, where dentists help their patients assume responsibility for achieving and maintaining their own oral health, and that of their children. Holistic care, which improves oral health and maximises ability to maintain oral health, should be regarded with the same importance and rewarded with a similar level of remuneration as 'traditional operative dentistry'. This paper gives an overview of a model of care involving the principles of this new approach, and the application of MID in clinical practice for primary teeth
Participant recruitment to FiCTION, a primary dental care trial – survey of facilitators and barriers
Objective To identify reasons behind a lower than expected participant recruitment rate within the FiCTION trial, a multi-centre paediatric primary dental care randomised controlled trial (RCT).
Subjects (materials) and methods An online survey, based on a previously published tool, consisting of both quantitative and qualitative responses, completed by staff in dental practices recruiting to FiCTION. Ratings from quantitative responses were aggregated to give overall scores for factors related to participant recruitment. Qualitative responses were independently grouped into themes.
Results Thirty-nine anonymous responses were received. Main facilitators related to the support received from the central research team and importance of the research question. The main barriers related to low child eligibility rates and the integration of trial processes within routine workloads.
Conclusions These findings have directed strategies for enhancing participant recruitment at existing practices and informed recruitment of further practices. The results help provide a profile of the features required of practices to successfully screen and recruit participants. Future trials in this setting should consider the level of interest in the research question within practices, and ensure trial processes are as streamlined as possible. Research teams should actively support practices with participant recruitment and maintain enthusiasm among the entire practice team
"I guess it looks worse to me, it doesn't look like there's been a problem solved but obviously there is":a qualitative exploration of children's and their parents' views of silver diamine fluoride for the management of carious lesions in children
Abstract Background Despite growing evidence to support the use of silver diamine fluoride (SDF) for managing carious lesions, and the increased interest in SDF worldwide, uptake in the UK remains limited. This study explored parents’ and children’s views and acceptability of SDF for the management of carious lesions in children. Methods Eleven semi-structured face-to-face interviews were conducted with 11 parent–child dyads recruited from patients attending Dundee Dental Hospital and School. Interviews were transcribed verbatim, coded and thematically analysed. Results Previous dental experience varied across all child participants. Of the 11 children, five had undergone general anaesthesia (GA) for multiple primary tooth extractions. Two had received SDF treatment. Child participants expressed concerns about being picked on by their peers, if they had discoloured anterior teeth. Younger children appeared less concerned about the discolouration and child’s gender did not appear to influence parents’ decision-making, nor the child’s preferences regarding the use of SDF. Parents considered SDF to be particularly useful for anxious or uncooperative children but raised concerns about potential bullying at schools due to the unacceptable dental aesthetics when SDF is applied to anterior teeth. They believed they may be judged by others as neglecting their child’s oral health due to the black staining. Both parents and children were more accepting of the SDF when applied to less-visible posterior teeth. Parents accepted the use of SDF if such treatment avoided extractions under GA. Conclusion Despite the unfavourable aesthetics of SDF (black staining), parents appreciated SDF treatment, especially for uncooperative or younger children. However, both parents and children shared concerns about bullying at schools as a consequence of the black staining. Raising awareness about SDF was identified as one approach to encourage the uptake of SDF
A Comparison of Ultraviolet, Optical, and X-Ray Imagery of Selected Fields in the Cygnus Loop
During the Astro-1 and Astro-2 Space Shuttle missions in 1990 and 1995, far
ultraviolet (FUV) images of five 40' diameter fields around the rim of the
Cygnus Loop supernova remnant were observed with the Ultraviolet Imaging
Telescope (UIT). These fields sampled a broad range of conditions including
both radiative and nonradiative shocks in various geometries and physical
scales. In these shocks, the UIT B5 band samples predominantly CIV 1550 and the
hydrogen two-photon recombination continuum. Smaller contri- butions are made
by emission lines of HeII 1640 and OIII] 1665. We present these new FUV images
and compare them with optical Halpha and [OIII], and ROSAT HRI X-ray images.
Comparing the UIT images with those from the other bands provides new insights
into the spatial variations and locations of these different types of emission.
By comparing against shock model calculations and published FUV spectroscopy at
select locations, we surmise that resonance scattering in the strong FUV
permitted lines is widespread in the Cygnus Loop, especially in the bright
optical filaments typically selected for observation in most previous studies.Comment: 21 pages with 10 figures. See http://www.pha.jhu.edu/~danforth/uit/
for full-resolution figure
Shocking Clouds in the Cygnus Loop
With Hubble Space Telescope Wide-Field Planetary Camera 2 observations of the
Cygnus Loop supernova remnant, we examine the interaction of an interstellar
cloud with the blast wave on physical scales of 10^15 cm. The shock front is
distorted, revealing both edge-on and face-on views of filaments and diffuse
emission, similar to those observed on larger scales at lower resolution. We
identify individual shocks in the cloud of density n~15 cm^-3 having velocity
v_s~170 km/s. We also find the morphologically unusual diffuse Balmer-dominated
emission of faster shocks in a lower-density region. The obstacle diffracts
these shocks, so they propagate at oblique angles with respect to the primary
blast wave. The intricate network of diffuse and filamentary H alpha emission
arises during the early stage of interaction between the cloud and blast wave,
demonstrating that complex shock propagation and emission morphology occur
before the onset of instabilities that destroy clouds completely.Comment: 7 pages including 5 figures; 1 color figure; to appear in the ApJ,
Oct. 10, 2001; full-resolution figures available at
http://www.pha.jhu.edu/~levenson/preprints/cyglhst.p
The Queensland Mango Genomics Initiative
Mango is an important industry for Queensland, Australia, with an annual value exceeding $80 million. The Kensington Pride cultivar, prized by consumers for desirable taste and colour characteristics, commands 60% of the domestic market though this market share has declined in recent years as new varieties, such as Calypsoâ„¢, get established with consumers. In 2005, the Queensland Government's Department of Agriculture and Fisheries commenced the Mango Genomics Initiative. This project brought together multidisciplinary teams of breeders, pathologists, sensory scientists, flavour chemists and molecular biologists to develop a suite of tools and inter-related data sets to support the accelerated development of new commercial mango varieties. An overview of the Mango Genomics Initiative will be presented here culminating in the generation of a draft Kensington Pride mango genome sequence
Single-molecule stretching shows glycosylation sets tension in the hyaluronan-aggrecan bottlebrush
Large bottlebrush complexes formed from the polysaccharide hyaluronan (HA)
and the proteoglycan aggrecan contribute to cartilage compression resistance
and are necessary for healthy joint function. A variety of mechanical forces
act on these complexes in the cartilage extracellular matrix, motivating the
need for a quantitative description which links their structure and mechanical
response. Studies using electron microscopy have imaged the HA-aggrecan brush
but require adsorption to a surface, dramatically altering the complex from its
native conformation. We use magnetic tweezers force spectroscopy to measure
changes in extension and mechanical response of an HA chain as aggrecan
monomers bind and form a bottlebrush. This technique directly measures changes
undergone by a single complex with time and under varying solution conditions.
Upon addition of aggrecan, we find a large swelling effect manifests when the
HA chain is under very low external tension (i.e. stretching forces less than
~1 pN). We use models of force-extension behavior to show that repulsion
between the aggrecans induces an internal tension in the HA chain. Through
reference to theories of bottlebrush polymer behavior, we demonstrate that the
experimental values of internal tension are consistent with a polydisperse
aggrecan population, likely caused by varying degrees of glycosylation. By
enzymatically deglycosylating aggrecan, we show that aggrecan glycosylation is
the structural feature which causes HA stiffening. We then construct a simple
stochastic binding model to show that variable glycosylation leads to a wide
distribution of internal tensions in HA, causing variations in the mechanics at
much longer length-scales. Our results provide a mechanistic picture of how
flexibility and size of HA and aggrecan lead to the brush architecture and
mechanical properties of this important component of cartilage
Shedding of Cryptosporidium in calves and dams – evidence of re-infection and shedding of different gp60 subtypes
One of the most common causes of calf diarrhoea is the parasite Cryptosporidium parvum. Two longitudinal studies were carried out on a dairy farm Scotland to determine the prevalence of Cryptosporidium species and subtypes in a group of calves and to determine whether dams were a possible source of calfhood infection. Fecal samples were collected from 25 calves from birth to 12 months in the first year. In the second year, fecal samples were collected from pregnant cows (n = 29) and their calves (n = 30) from birth to 6 months. The samples were tested for Cryptosporidium and speciated. Cryptosporidium parvum-positive samples were subtyped by GP60 fragment analysis. All calves in both studies shed Cryptosporidium during the study period. Cryptosporidium parvum was the predominant species detected in calves ⩽6 weeks of age and at 6 months of age, C. bovis and C. ryanae were detected in calves older than 4 weeks of age but ⩽6 months of age. The prevalence of Cryptosporidium was higher in younger animals than in older animals. GP60 subtyping revealed two subtypes in calves on this farm (IIaA15G2R1 and IIaA19G2R1) that differed in frequency by age. Adult cattle also shed C. parvum, of four gp60 genotypes
Perfluoroalkyl substances and kidney function in chronic kidney disease, anemia, and diabetes
Background: Anemia often complicates chronic kidney disease (CKD), leading to insufficient tissue oxygenation and hypoxic injury, the factor thought to underlie progression from CKD to renal failure. Perfluorocarbons are potent oxygen transporters used in organ preservation and synthetic blood development. Data are scarce on their relationship with kidney function, especially in diabetes where anemia and hypoxia are more prevalent. We investigated the relationship of perfluoroalkyl acids (PFAS) with kidney function and variation by diabetes and anemia status.
Methods: Data on 53,650 adults (5,210 with diabetes) were obtained from the C8 Health Project. CKD was defined as an estimated glomerular filtration rate (eGFR) \u3c60 mL/min/1.73 m2. Four PFAS were investigated: perfluorohexane sulfonate (PFHxS), perfluorooctanoic acid, perfluorooctane sulfonate, and perfluorononanoic acid.
Findings: Each PFAS was positively associated with eGFR among those with CKD or anemia; this was the strongest among those with both CKD and anemia, followed by those with CKD uncomplicated by anemia. These relationships were more pronounced among those with diabetes (all P\u3c0.01). In the absence of both CKD and anemia, PFAS was inversely associated with eGFR. Among persons with both anemia and diabetes, when further stratified by CKD stage, compared to an eGFR \u3c30, ORs (95% CI) for being in the eGFR ≥ 90, 60–89, 45–59, and 30–45 range, respectively, were 3.20 (2.00–5.13), 2.64 (1.83–3.80), 3.18 (2.17–4.67), and 1.99 (1.38–2.86) for each ng/dL increase in PFHxS. Results were similar for each PFAS.
Interpretation: PFAS are inversely associated with kidney function in CKD and diabetes, with a stronger relation observed when anemia is present
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